for the last one, not that I'm offering to write it, or that there is space for it, but you *could*, without using a separate computer:

1. initialize the guino with the odometer reading
2. have it track max speed (store it and odo in eprom)
3. have it reset max speed/update odo with password (up to 10 digit number for password would be easy)

So you can track max speed (or some sort of average) confidently, or your kid will figure out how to hack it, it's all good